In persons with congenital nystagmus (CN), rhythmic to-and-fro oscillations of the eyes produce nearly continuous motion of the retinal image. Nevertheless, individuals with CN rarely report the visual world to be moving or smeared. Recent observations indicate that the retinal image motion that accompanies voluntary smooth pursuit and saccadic eye movements in normal observers results in less perceived motion smear than does comparable motion of the retinal image when the eyes are still. The underlying premise of the studies described in this proposal is that the mechanisms responsible for the attenuation of perceived motion smear during normal eye movements are similar to those that mediate the relatively clear vision that is reported by persons with CN. The overall goal of this research project is to characterize the attenuation of perceived motion smear that occurs during normal eye movements and to evaluate possible underlying mechanisms. This goal will be addressed in the context of four specific aims: (1) Determine whether perceived motion smear is attenuated during normal involuntary eye movements, which are presumed to be neurologically similar to the involuntary ocular oscillations in persons with CN, (2) Identify whether the presence of an extra-retinal signal for eye or gaze movement, or the-perception of a stationary target in space is the necessary condition for the attenuation of perceived motion smear, (3) Determine how the attenuation of perceived motion smear during eye movements interacts with the motion deblurring of complex visual scenes that is based on metacontrast masking, and (4) Assess whether a hypothesized increase in temporal processing speed during eye movements can contribute to the reduction of perceived motion smear. The proposed program of research will clarify the mechanisms by which perceived motion smear is attenuated during normal eye movements, and will provide evidence about the likely contributions of these mechanisms to the clarity of vision reported by persons with CN.